1. Field of the Invention
This invention relates generally to an ion beam processing system and, more particularly, to an advanced ion beam process for producing ultra dense and ultra fast integrated circuits.
2. Discussion of the Related Art
The dimensions of integrated circuits are continually decreasing in order to maximize speed and efficiency while the density and complexity of these integrated circuits continue to increase. As this occurs, the cost of producing such integrated circuits dramatically rises while at the same time lowering the production yield of such integrated circuits. This results because many microelectronic manufacturing problems arise from human contact and error existing in process and equipment operations. Moreover, as new processing strategies develop for the manufacture of complex submicron integrated circuits, an increasing number of processing steps will be added to complete each level of these complex submicron integrated circuits. This will in turn require additional capital equipment while reducing the production yield, throughput and flexibility of these manufacturing facilities even more. Consequently, the manufacturers producing such complex submicron integrated circuits will continuously be influenced to reduce the extensive cost for labor and capital equipment while attempting to increase throughput and production yields.
Currently, lithography is the key manufacturing and patterning step in all integrated circuit fabrication processes. The lithography process employs a photoresist which is a photosensitive plastic. This resist is typically spun on a wafer, baked, and exposed in an intricate pattern, usually by ultraviolet light, although X-rays and electronic beams may also be used. After developing and baking the wafer, the wafer surface is left partly covered by the resist which is an inert organic film that "resists" various treatments to which the bare surface of the wafer is subjected. Such treatments may include material removal by a wet chemical etch or gaseous plasma, doping by ion implantation (i.e. broad beam), or addition of material by evaporation (i.e. lift off). This patterned alteration of the wafer surface using lithography is a slow and tedious multi-step process which requires extensive human contact, as well as positioning the wafer at various work stations all situated in a "clean" room. Moreover, this type of process treats the whole wafer in the same way, and thus is not very flexible.
Photolithography is currently the main lithographic tool for processing patterns in resists above 0.35 microns. However, present and future microelectronics are growing smaller and require minimum feature sizes below 0.25 microns. As microelectronics geometries become even more intricate, geometries will further reduce in size and each process step will become more complex, resulting in additional production yield loss. While a number of lithography techniques such as eximer laser, phase shift, projection ion, X-ray lithography (XRL) or electron-beam lithography (EEL), could be used for production on this scale, all of these techniques are now close to their theoretical performance limits. Pushed to these limits, each of these techniques have weaknesses which present difficult problems.
Each of the above mentioned techniques will produce complex submicron integrated circuits. However, these techniques have several drawbacks associated with them, including additional weaknesses as the complex submicron integrated circuits become smaller and more densely populated. These drawbacks include higher operating costs, additional manufacturing steps, large complex tooling and manufacturing facilities, reduced production yields and ultimate limits on the size integrated circuits that can be produced.
What is needed then is a method of fabricating ultra dense and ultra fast integrated circuits based on a low dose, resistless, in-situ focused ion beam processing system. This will in turn reduce the operating costs, manufacturing steps and size of the manufacturing facility, while at the same time increasing the production yield and allow the manufacture of more complex submicron integrated circuits. It is, therefore, an object of the present invention to provide such a method.